With the respective development of mobile communications and broadband wireless access technologies, services of the two technologies interpenetrate each other. To cater to a demand of broadband mobile communications and to cope with a challenge of mobile broadband communications, the Third Generation Partnership Project (the 3rd generation partnership project, 3GPP) working group raises a higher performance requirement for communications systems, such as, higher requirements for a peak rate and system bandwidth. To meet these requirements, the 3GPP Long Term Evolution Advanced (long term evolution advanced, LTE-A) introduces carrier aggregation (Carrier Aggregation, CA).
In CA, larger bandwidth can be obtained by aggregating multiple continuous or discontinuous component carriers (component carrier, CC), thereby improving a peak data rate and a system throughput, and also solving a problem of discontinuous spectra of an operator. A user equipment (User Equipment, UE) can support aggregation of multiple CCs in uplink and downlink separately, and the CCs may be at a same band (band) or different bands. The CCs aggregated by the UE are provided by a same base station, for example, multiple co-site CCs provided by the base station, or multiple non-co-site CCs separately provided by the base station and a remote radio head (Remote Radio Head, RRH) of the base station.
A conventional LTE-A technology only supports aggregation of CCs provided by the same base station, and CA cannot be performed when CCs of different base stations have a common coverage area. Therefore, a UE located in the common coverage area of the CCs of the different base stations requires a handover (handover) to a cell (cell) in a good radio condition in a moving procedure, and a handover procedure may lead to a service delay or interruption, and reduce a peak rate and a throughput.